SMP: fix build failure if SMP=y and SYS_CLOCK_EXISTS=n

Fix build failure for the SMP configurations without sysclock.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>
diff --git a/kernel/smp.c b/kernel/smp.c
index 2ec2ea4..8ae2116 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -85,7 +85,9 @@
 
 	wait_for_start_signal(arg);
 	z_dummy_thread_init(&dummy_thread);
+#ifdef CONFIG_SYS_CLOCK_EXISTS
 	smp_timer_init();
+#endif
 
 	z_swap_unlocked();